Apples with Apples - Association of numerical relativity groups, with the aim of developing standards for comparing the groups' different simulation codes and the results obtained therewith.
APS Topical Group on Gravity - Topical interest group of the American Physical Society. Includes a brief description of the group, information about prizes, and its newsletters "Matters of gravity".
The International Light Cone Advisory Committee (ILCAC) - Dedicated to efforts to solve quantum field theories by use of a special, relativity-based method known as light-cone quantization. Includes list of members and information about the committee's workshops and meetings.
LISA International Science Community - Website for the community of scientists involved in doing research for and with the proposed space-borne gravitational wave detector LISA.